I've found a pretty successful way of dealing with inappropriate client requests. Actually, it is a wonderful method that I use on myself all the time, and use it on requests that seem perfectly reasonable as well.
Whenever I find myself, or the client, straying into *application* before we've really fleshed out the concept, I bring it back to the concept by asking " Ok, what do you hope to achieve with ____________? What are your goals?"
Usually, when the client considers his or her goals, he or she may realize an idea is inappropriate, come up with another, or be satisfied with fleshing out the goals more specifically, leaving the application to US.
For instance, client wants a jazzy flash intro. That's application. The goal may be to put across their brand in a dynamic and engaging manner, or to set a mood for the rest of the site. Then we take those as guidelines:
1) Establish a mood for the site
2) Potray the brand in a dynamic and engaging manner.
And often that feels concrete enough to the client to let US hack at it ourselves.
You should do this to yourself as well. It helps avoid knee-jerk "solutions."